In one type of conventional two-cycle internal combustion engine, a reed valve is positioned in the path of flow of the fuel/air charge between the carburetor and the crankcase. It acts as a one-way check valve, opening and closing to meet the downstream demands of the engine.
Such valves are well known and widely used. They do, however, have complications. For example, the engine crankcase where the valve is mounted gets hot in operation. If the entire valve is made of metal, it soon becomes so hot that the fuel gasifies and the engine often stalls out. To overcome this problem, the valve body is generally made of a heat-insulating material. A metal reed plate is mounted to the plastic body, and its free end seats against the plastic body when the valve is closed. This arrangement keeps the reed valve cool enough that it does not adversely affect the fuel/air charge.
As so often happens, a cure for one problem may create a problem of its own, and this has in fact occurred. The plastic valve body is an injection molded article. Because of the complicated shapes involved, the body has various thicknesses. When the body is molded, it is very difficult to maintain a flat surface in high volume production. Furthermore, when the body is heated, as happens in a running engine, stresses which have been molded into the part are relieved resulting in distortions of the plastic valve seat. Then an imperfect closing action sometimes results that adversely affects the engine operation.
It is an object of this invention to provide a reed valve with a thermally-insulating body and a valve seat that does not distort with rising temperatures.